The supervisors voted in February to draft a temporary ban on medical marijuana cultivation and study a permanent ban, citing concerns about environmental effects and safety issues. They passed a 45-day ban last month, which was set to expire this week if the board had not acted.

County planning officials asked for a 10-month extension so they could conduct a "comprehensive zoning study" and propose a system for regulating growing operations.

Marijuana dispensaries are already banned in unincorporated areas.

Medical marijuana patients and advocates pushed back against the ban.

"We have people who have seizures, we have people who have glaucoma, we have those with degenerative bone diseases, chronic pain, and unfortunately they are denied their medications now because of the closure of our cannabis clinics, our dispensaries," said Greg Hernandez of Lake Los Angeles. "The only thing that this ban has gone ahead and done is reignited the black market right here in the Antelope Valley."

Josh Drayton, a former aide to state Senate leader Kevin de León (D-Los Angeles), who now serves as deputy director of the California Cannabis Industry Assn., said polling has shown widespread support for the statewide marijuana legalization measure and asked the board to bring in industry representatives to help develop a regulatory structure.

"Cannabis is not going away," he said. "I would encourage the board to get ahead of this instead of behind."

The supervisors have also battled with the wine industry over stringent restrictions on vineyards in the Santa Monica Mountains. Kuehl said county planners need to also look at the environmental effects of marijuana cultivation.

"I don't want to regulate grapes more than I regulate other crops, including marijuana," she said.